Based on the part number and description, here's a clear breakdown of Relay 12088567 (also known as 85578 or 8567):
Type: Standard Automotive ISO Mini Relay
Function: Multipurpose Switching Relay.
Key Specifications:
Voltage: 12 Volt DC.
Terminals: 4-Pin (SPST - Single Pole Single Throw, Normally Open).
Pin Configuration (Standard ISO):
85: Coil Ground (-)
86: Coil Power (+)
87a: Not Present (This relay doesn't have a Normally Closed contact)
30: Common Contact (Input - Power Source)
Common Applications: This relay is compatible with or designed to fit circuits controlling:
Fog Lights
Headlights (Often High Beams or specific circuits)
Horn
Starter / Ignition Circuits
Fuel Pump (ECM/PCM controlled)
Flashers (Turn Signals, Hazard Lights)
Cooling Fans
Various other accessories and engine management functions.
Compatibility: Widely used across many General Motors (GM) vehicles, including:
Buick
Cadillac
Chevrolet
GMC
Pontiac
Oldsmobile
Saturn
Hummer (H2, H3)
Saab (GM-era)
Location: Found in the underhood fuse/relay box(es) and sometimes interior fuse panels. It's a very common relay in GM vehicles from the late 1990s through the 2010s (and often interchangeable within that period).
Important Notes:
"Multipurpose": While marketed for specific uses (Fog, Headlights, Horn, Starter, ECM/Flashers), this is fundamentally a generic switching relay. Its actual function depends entirely on which circuit it's plugged into within your specific vehicle. A physically identical relay might control the horn in one car and the fuel pump in another.
Interchangeability: This relay design is an industry standard . make functionally identical relays that will work in the socket designed for part number 12088567/85578/8567.
If you're troubleshooting or replacing:
Identify the Faulty Relay: Refer to your vehicle owner's manual or the fuse/relay box diagram to locate which specific circuit (e.g., Horn, Fog Lights, Fuel Pump) this relay controls in your car.
Swap Test: Often the easiest way to test is to swap this relay with another identical one in the box (e.g., swap the horn relay with the fog light relay). If the problem moves, you've found the bad relay.
Check Socket & Fuse: Before blaming the relay, ensure the fuse for the circuit is good and that there are no signs of corrosion or damage in the relay socket.
In short: Relay 12088567/85578/8567 is a standard 12V 4-pin ISO mini relay widely used as a generic switching component for lights, horns, ignition, flashers, and engine management systems in many GM vehicles. Its specific function depends on where it's plugged in.